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Nondestructive analysis of structure and stresses by ultrasonic and micromagnetic methods

: Höller, P.

Bussiere, J.F.:
Nondestructive Characterization of Materials II
New York/N.Y.: Plenum Press, 1987
ISBN: 0-306-42610-2
International Symposium on Nondestructive Characterization of Materials <2, 1986, Montreal>
Fraunhofer IZFP ()
akustisches Barkhausenrauschen; Eigenspannung; Einhärtetiefe; elektromagnetische Ultraschallwandlung; Gefüge; Korngröße; Kriechschädigung; Lastspannung; magnetisches Barkhausenrauschen; Magnetostriktion; Materialcharakterisierung; photoakustische Mikroskopie; pore; Schleifen; Schleiffehler; Schweißeigenspannung; Schweißnaht; Turbinenschaufel; Überlagerungspermeabilität; Ultraschall

During operation of machinery or use of components, strength and toughness of materials are slowly degraded by load induced fatigue, creep or corrosion. Here, temperature is a very important parameter. Any degradation starts with changes of the microstructure of the materials and only grows slowly to cracklike defects, significant from the fracture mechanic point of view; but already changes of microstructure have influence on strength and toughness, especially of high strength steels. Therefore materials testing for quality assurance is needed not only during fabrication but also during operation. In safety related cases more and more the quality of the real components (not only small specimens) has to be tested nondestructively, and any testing for quality assurance during operation must be performed nondestructively. This contribution gives a survey on the R and D activities of the IzfP in the last few years dealing with evaluation of defects, structure of materials, residual and lo ad induced stresses which include grain size evaluation from ultrasonic backscatter, assessment of creep damage from ultrasonic velocity measurements, detection and imaging of fatigue damage by photoacoustic microscopy, ultrasonic measurement of macrostresses by polarized shear waves and application of micromagnetic multiparameter microstructure and stress analysis (3MA) to the control of laser hardening, flame hardening of turbine blades and the detection of grinding defects. (IZFP)